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98 results on '"Lowman, Andrew E."'

2. Reconfigurable dynamic optical system design, test, and data analysis

Author

Kim, Dae Wook, primary, Aftab, Maham, additional, Trumper, Isaac L., additional, Graves, Logan R., additional, Quach, Henry, additional, Kang, Hyukmo, additional, Yoo, Hyemin, additional, Lowman, Andrew E., additional, Smith, Greg A., additional, Dubin, Matthew B., additional, Oh, Chang-Jin, additional, Hyatt, Justin, additional, Davila-Peralta, Christian, additional, and Choi, Heejoo, additional

Published
2020
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3. Occulting focal plane masks for Terrestrial Planet Finder Coronagraph: design, fabrication, simulations and test results

Author

Balasubramanian, Kunjithapatham, Hoppe, Daniel J, Halverson, Peter G, Wilson, Daniel W, Echternach, Pierre M, Shi, Fang, Lowman, Andrew E, Niessner, Albert F, Trauger, John T, and Shaklan, Stuart B

Subjects
Lunar And Planetary Science And Exploration
Abstract

Occulting focal plane masks for the Terrestrial Planet Finder Coronagraph (TPF-C) could be designed with continuous gray scale profile of the occulting pattern such as 1-sinc2 on a suitable material or with micron-scale binary transparent and opaque structures of metallic pattern on glass. We have designed, fabricated and tested both kinds of masks. The fundamental characteristics of such masks and initial test results from the High Contrast Imaging Test bed (HCIT) at JPL are presented.

Published
2005

5. Modulation transfer function measurement of sparse-array sensors using a self-calibrating fringe pattern

Author

Greivenkamp, John E. and Lowman, Andrew E.

Subjects
Functions, Modular -- Research, Sensors -- Research, Astronomy, Physics
Abstract

A simple method for the measurement of the pixel modulation transfer function (MTF) of sparse-array (extended MTF) sensors has been developed. We use a phase-shifting Twyman-Green interferometer to generate a series of single spatial-frequency fringe patterns incident on the sensor. The resulting signal modulation is measured. We achieve self-calibration by restricting the measured spatial frequencies to multiples of the Nyquist frequency. The aliased patterns at these frequencies are unique and easily identifiable. Spatial frequencies of 480 cycles/mm are generated and measured. This frequency value is more than ten times that of the sensor sampling frequency. The expected MTF shape is obtained at multiples of the sampling frequency. At odd multiples of the Nyquist frequency, the MTF's are affected by the electronic bandwidth and cross talk in the charge-injection device sensor.

Published
1994

6. Wavefront Control Testbed (WCT) Experiment Results

Author

Burns, Laura A, Basinger, Scott A, Campion, Scott D, Faust, Jessica A, Feinberg, Lee D, Hayden, William L, Lowman, Andrew E, Ohara, Catherine M, and Petrone, Peter P., III

Subjects
Space Sciences (General)
Abstract

The Wavefront Control Testbed (WCT) was created to develop and test wavefront sensing and control algorithms and software for the segmented James Webb Space Telescope (JWST). Last year, we changed the system configuration from three sparse aperture segments to a filled aperture with three pie shaped segments. With this upgrade we have performed experiments on fine phasing with line-of-sight and segment-to-segment jitter, dispersed fringe visibility and grism angle;. high dynamic range tilt sensing; coarse phasing with large aberrations, and sampled sub-aperture testing. This paper reviews the results of these experiments.

Published
2004

9. Developmental Cryogenic Active Telescope Testbed, a Wavefront Sensing and Control Testbed for the Next Generation Space Telescope

Author

Leboeuf, Claudia M, Davila, Pamela S, Redding, David C, Morell, Armando, Lowman, Andrew E, Wilson, Mark E, Young, Eric W, Pacini, Linda K, and Coulter, Dan R

Subjects
Astronomy
Abstract

As part of the technology validation strategy of the next generation space telescope (NGST), a system testbed is being developed at GSFC, in partnership with JPL and Marshall Space Flight Center (MSFC), which will include all of the component functions envisioned in an NGST active optical system. The system will include an actively controlled, segmented primary mirror, actively controlled secondary, deformable, and fast steering mirrors, wavefront sensing optics, wavefront control algorithms, a telescope simulator module, and an interferometric wavefront sensor for use in comparing final obtained wavefronts from different tests. The developmental. cryogenic active telescope testbed (DCATT) will be implemented in three phases. Phase 1 will focus on operating the testbed at ambient temperature. During Phase 2, a cryocapable segmented telescope will be developed and cooled to cryogenic temperature to investigate the impact on the ability to correct the wavefront and stabilize the image. In Phase 3, it is planned to incorporate industry developed flight-like components, such as figure controlled mirror segments, cryogenic, low hold power actuators, or different wavefront sensing and control hardware or software. A very important element of the program is the development and subsequent validation of the integrated multidisciplinary models. The Phase 1 testbed objectives, plans, configuration, and design will be discussed.

Published
1998

10. Optical Design of the Developmental Cryogenic Active Telescope Testbed (DCATT)

Author

Davila, Pam, Wilson, Mark, Young, Eric W, Lowman, Andrew E, and Redding, David C

Subjects
Optics
Abstract

In the summer of 1996, three Study teams developed conceptual designs and mission architectures for the Next Generation Space Telescope (NGST). Each group highlighted areas of technology development that need to be further advanced to meet the goals of the NGST mission. The most important areas for future study included: deployable structures, lightweight optics, cryogenic optics and mechanisms, passive cooling, and on-orbit closed loop wavefront sensing and control. NASA and industry are currently planning to develop a series of ground testbeds and validation flights to demonstrate many of these technologies. The Deployed Cryogenic Active Telescope Testbed (DCATT) is a system level testbed to be developed at Goddard Space Flight Center in three phases over an extended period of time. This testbed will combine an actively controlled telescope with the hardware and software elements of a closed loop wavefront sensing and control system to achieve diffraction limited imaging at 2 microns. We will present an overview of the system level requirements, a discussion of the optical design, and results of performance analyses for the Phase 1 ambient concept for DCATT

Published
1997

16. Interferometer errors due to the presence of fringes

Author

Lowman, Andrew E. and Greivenkamp, John E.

Subjects
Interferometry -- Research, Interferometers -- Research, Astronomy, Physics
Abstract

Phase-shifting interferometry permits analysis of complex interferograms. However, the measurement accuracy is reduced as the number of fringes is increased. The wavefront from a defocused spherical surface is used to demonstrate this degradation for several different transmission reference objectives.

Published
1996

29. Terrestrial Planet Finder coronagraph

Author

Ford, Virginia G., primary, Hull, Anthony B., additional, Shaklan, Stuart B., additional, Levine, Marie B., additional, White, Mary L., additional, Lowman, Andrew E., additional, and Cohen, Eri J., additional

Published
2003
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31. Wavefront control testbed integrated software system

Author

Burns, Laura A., primary, Basinger, Scott A., additional, Beck, Terrence L., additional, Deering, Jennifer, additional, Tonnu, Daoanh, additional, Lindler, Don J., additional, Lowman, Andrew E., additional, Morris, Robert, additional, Ohara, Catherine M., additional, Petrone III, Peter, additional, Redding, David C., additional, Schott, Jeff, additional, Stoner, Sara M., additional, and Wheeler, J. Ladd, additional

Published
2003
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33. Optical design and performance of the NGST wavefront control testbed

Author

Petrone III, Peter, primary, Basinger, Scott A., additional, Burns, Laura A., additional, Bowers, Charles W., additional, Chu, Andrew, additional, Cohen, David, additional, Davila, Pamela S., additional, Dean, Bruce H., additional, Dogota, Peter, additional, Fitzmaurice, Michael W., additional, Green, Joseph J., additional, Ha, Kong, additional, Hayden, William L., additional, Lindler, Don J., additional, Lowman, Andrew E., additional, Ohara, Catherine M., additional, Wilson, Mark E., additional, Redding, David C., additional, Shi, Fang, additional, and Zukowski, Barbara J., additional

Published
2003
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34. Phase retrieval camera for testing NGST optics

Author

Lowman, Andrew E., primary, Redding, David C., additional, Basinger, Scott A., additional, Cohen, David, additional, Faust, Jessica A., additional, Green, Joseph J., additional, Ohara, Catherine M., additional, and Shi, Fang, additional

Published
2003
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41. Wavefront control testbed experimental results.

Author

Burns, Laura A., Basinger, Scott A., Campion, Scott D., Faust, Jessica A., Feinberg, Lee D., Green, Joseph J., Hayden, William L., Lowman, Andrew E., Ohara, Catherine M., Petrone III, Peter P., Redding, David C., Shi, Fang, Van Buren, David, and Zukowski, Barbara

Published
2004
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44. Optical design and performance of the NGST wavefront control testbed.

Author

Petrone III, Peter, Basinger, Scott A., Burns, Laura A., Bowers, Charles W., Chu, Andrew, Cohen, David, Davila, Pamela S., Dean, Bruce H., Dogota, Peter, Fitzmaurice, Michael W., Green, Joseph J., Ha, Kong, Hayden, William L., Lindler, Don J., Lowman, Andrew E., Ohara, Catherine M., Wilson, Mark E., Redding, David C., Shi, Fang, and Zukowski, Barbara J.

Published
2003
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46. Wavefront control testbed integrated software system.

Author

Burns, Laura A., Basinger, Scott A., Beck, Terrence L., Deering, Jennifer, Tonnu, Daoanh, Lindler, Don J., Lowman, Andrew E., Morris, Robert, Ohara, Catherine M., Petrone III, Peter, Redding, David C., Schott, Jeff, Stoner, Sara M., and Wheeler, J. Ladd

Published
2003
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50. Wavefront control for a segmented deployable space telescope.

Author

Redding, David C., Basinger, Scott A., Cohen, David, Lowman, Andrew E., Shi, Fang, Bely, Pierre Y., Bowers, Charles W., Burg, Richard, Burns, Laura A., Davila, Pamela S., Dean, Bruce H., Mosier, Gary E., Norton, Todd A., Petrone III, Peter, Perkins, Brendon D., and Wilson, Mark E.

Published
2000
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